Relations between the US and China have been through some difficult times in the half century since the People's Republic of China came into being. BBC News Online charts the highs and lows:

2002

25 Oct: Chinese President Jiang Zemin visits President George Bush at his Texas ranch. They agree to work together to solve the crisis created by North Korea's admission that it has nuclear weapons.

12 July: A new Pentagon report to Congress questions China's commitment to a peaceful settlement of its differences with Taiwan. It also highlights the threat China poses to neighbouring countries.

1 May: President Bush welcomes China's presumed future leader Hu Jintao to the White House for talks. The meeting is broadly deemed a success, but Mr Hu's low-key approach, while avoiding any new conflicts, disappoints some analysts.

Apr: Angry over US dealings with Taiwan, China refuses a request by the USS Curtis Wilbur to make a port call at Hong Kong.

21-22 Feb: President Bush makes his second visit to China in three months, flying into Beijing on the symbolically important 30th anniversary of the summit between former leaders Richard Nixon and Mao Zedong. The visit goes smoothly but little progress is made on key areas of conflict.

2001

Nov: China joins the World Trade Organisation.

Oct: George Bush and Jiang Zemin meet for the first time in Shanghai, at an Asia Pacific Economic Co-operation (Apec) summit. Mr Jiang backs US war on terrorism and says China is willing to work to develop a "constructive relationship" with the US.

May: To Beijing's fury, the White House allows Taiwanese President Chen Shui-bian to visit the US.

Apr: US spy plane makes emergency landing on southern Chinese island of Hainan, after a collision with a Chinese fighter jet. China accuses the US plane of ramming its aircraft, but the US says it was an accident. China releases the 24 crew only after Mr Bush says he is "very sorry" that a Chinese pilot died in the incident.

23 Mar: China confirms that an officer of the Chinese People's Liberation Army has defected to the US during a visit.

22 Mar: Chinese Vice-Premier Qian Qichen meets Bush at the White House. He warns the US against selling new weapons to Taiwan. Bush says the US will not take any actions that would threaten China.

7 Mar: Beijing increases defence budget to about $17bn. The US says it will keep an eye on China's military build-up.

6 Mar: Beijing warns the US not to go ahead with the planned sale of sophisticated weapons to Taiwan. It also rejects US allegations that Chinese companies helped Iraq to upgrade its air defences in defiance of United Nations sanctions.

Jan: New US President George W Bush makes it clear he does not regard China as a "strategic partner". China fears his support for a National Missile Defence system.

2000

Sep: US Senate passes Permanent Normal Trade Relations (PNTR) bill, which guarantees Chinese goods the same low-tariff access to the US market as products from most other nations.

Sep: China welcomes Clinton's decision to delay the development of an anti-missile defence shield.

Jun: US secretary of state Madeleine Albright meets senior Chinese leaders in Beijing, the first by such a senior official since the Belgrade embassy bombing in 1999.

May: US House of Representatives votes to normalise trade relations with China, and to set up a commission to monitor China's human rights record.

Apr: The US decides to sell a new military package to Taiwan but defers a decision on some controversial weapons, including submarines, anti-submarine aircraft and new Aegis class destroyers.

Nov 99: US and China agree terms for China's entry to the World Trade Organisation (WTO).

Sep 99: US and China resume bilateral WTO negotiations.

8 May 99: Nato warplanes taking part in Yugoslavia air raids, accidentally bomb the Chinese Embassy in Belgrade, sparking outrage from China. It suspends WTO talks.

Jun 98: Bill Clinton is the first US president to visit China since Tiananmen Square. He criticises the violent crushing of the 1989 demonstrations and urges China to respect and preserve the basic human rights of its people. The trip is considered a success, but fails to bring agreement on economic reforms that China must meet to gain entry into the WTO.

In Shanghai, Clinton strongly reaffirms his "three Nos" policy:

No support for Taiwan independence

No recognition of a separate Taiwanese Government

No backing for Taiwanese membership of international organisations

Jun 98: US Senate Republicans investigate allegations that China gained sensitive missile technology by launching a US satellite, and that the Chinese military illegally contributed to the Democrats' 1996 election campaign. China denies allegations.

Jun 98: Washington and Beijing jointly propose meeting of five permanent members of United Nations Security Council to discuss nuclear tests by India and Pakistan after Clinton and Jiang talk on new telephone "hotline".

Apr 98: China releases prominent dissident Wang Dan from prison and forces him into exile in the US.

Jan 98: US Defence Secretary William Cohen visits China to discuss closer military ties, visits secret air base in Beijing.

Nov 97: China releases prominent dissident Wei Jingsheng from prison and forces him into exile in the US. Clinton and Jiang meet in Vancouver, Canada before the start of APEC forum.

Oct 97: President Jiang Zemin is the first Chinese president to visit the US in 12 years.

July 97: China regains control of Hong Kong from the UK. It improves relations between China and the US.

Nov 96: Clinton and Jiang meet at APEC forum in Manila, agree to exchanges of officials leading to presidential visits.

Mar 96: China holds missile tests off Taiwan to intimidate voters against Lee Teng-hui, running in the island's first direct presidential elections. China fears he is pro-independence. The US sends two aircraft-carrier battle groups to the area in a show of support for Taiwan. Lee wins election by a landslide.

Aug 95: Chinese court sentences Chinese-American human rights activist Harry Wu, to 15 years in prison for sneaking into the country to document prison labour. However he is instead deported.

May 95: President Clinton authorises private visit to New York by Taiwan's Lee Teng-hui, reversing 15-year-old policy of denying visas to Taiwan leaders. China recalls its ambassador to Washington in protest.

Sep 93: Clinton launches a policy of "constructive engagement" with China, according to a White House document.

Jan 93:Clinton comes into office with policy of using economic leverage to promote democracy in China. He insists that Most Favoured Nation trading status for China be linked to specific improvements in human rights conditions. During presidential campaign he had accused President Bush of "coddling" China's leaders, and pledged to pursue a tougher policy.

Sep 92: US President Bush approves the sale of 150 F-16 fighter jets to Taiwan, overturning a decade of US policy.

July 89: US National Security Adviser Brent Scowcroft meets Chinese leaders in a secret mission to Beijing to reaffirm relations following Tiananmen Square massacre.

4 Jun 89: China's People's Liberation Army crushes student-led pro-democracy demonstrations around Beijing's Tiananmen Square. The United States and other Western countries impose sanctions on Beijing.

Feb 89: US President George Bush visits China. He invites dissidents to a banquet. China responds by forcibly preventing one, Fang Lizhi, from attending.

Aug 82: In a third joint communiqué, the US pledges not to increase and to gradually reduce arms sales to Taiwan.

Jan 82: China opposes US decision to sell aircraft to Taiwan.

Apr 79: US Congress passes Taiwan Relations Act reaffirming commitment to Taiwan and pledging to maintain arms sales to the island. China is unhappy with the bill.

Jan 79: China and the US establish diplomatic relations after US President Jimmy Carter switches recognition to Beijing from Taipei. A joint communiqué says Washington will maintain unofficial links with Taiwan. Soon afterwards, China's Vice Prime Minister Deng Xiaoping visits the US. At a Texas rodeo he appears in a traditional Stetson hat, creating a more friendly image of China to the US public.

Sept 1976: Mao Zedong dies.

Dec 75: US President Gerald Ford visits China.

Feb 72: US President Richard Nixon meets Mao Zedong in Peking. Nixon signs the Shanghai Joint Communiqué declaring that there is "one China" and that Taiwan is a part of China.

July 71: China invites US ping-pong team to play in Peking - dubbed "ping pong" diplomacy. Henry Kissinger, former US Secretary of State, makes a secret visit to China to arrange for a trip by Nixon.